In an existing refrigeration cycle apparatus including an ejector, a variable throttle mechanism 31 is mounted at an outlet of a condenser 12, a fixed throttle 19 is mounted on one of branching paths on the downstream side of the variable throttle mechanism 31, and an ejector 15 is mounted on the other branching path (e.g., see Patent Literature 1).
Flow rates of a refrigerant passing through the fixed throttle 19 and a nozzle 15a of the ejector 15 are previously set to provide such an optimum flow ratio that the cooling capacity of the entire system is at its maximum, and this is achieved by setting the refrigerant flow passage area of the nozzle portion 15a of the ejector 15, the dimensions of a mixing portion 15c and a diffuser portion 15d, and the opening degree of the fixed throttle 19 to appropriate values.